Number of Yelkouan (YS), Balearic (BS)and unknown shearwaters that moulted their feathers in the same year.

Bird species from dataset 1 was inferred based in the agreement in species assignment of at least three of the following criteria: plumage colouration, biometric measurements, genetic and stable isotope data (see table 2). Birds with less than 3 criteria agreeing in species assignment were considered unknown shearwaters. Bird species from dataset 2 was inferred based on the agreement on species assignment by plumage colouration, discriminant functions of biometric measures and stable isotope data. Birds from dataset 2 were considered unknown shearwaters if one of the criteria disagreed in species identification. All birds from dataset 1 were used in cluster analysis (except the 10 Yelkouan shearwaters (YS) from Hyères Islands (France), which were not used in geometric morphometric cluster analysis). All birds from dataset 1, expect unknown shearwaters, were used in species identification and discriminant function. All birds from both dataset, except the unknown shearwaters, were used for checking annual variation in stable isotope data.Number of Yelkouan (YS), Balearic (BS)and unknown shearwaters that moulted their feathers in the same year.